A conventional brake cable adjustable device known to applicant is disclosed in U.S. Pat. No. 5,448,927 to Avid Enterprises, Inc., issued on Sep. 12, 1995 and having the title of "Adjustable Leverage Brake Lever". In the above identified patent, the jack bolt extends through the mounting arm from the outside of the mounting arm so that when adjusting the leverage applied to the brake cable, the user simply rotates the knurled head of the jack bolt. By this way, the distance between the pivotable arm can be varied. Nevertheless, the knurled head of the jack bolt is exposed on and extending from the outside of the mounting arm so that the knurled head could tangle, or even hurt the user or a person passing beside the bicycle. Furthermore, the direction of the tension force of the brake cable is substantially perpendicular to the direction of movement of the cylinder and the jack bolt so that the user has to take effort to rotate the jack bolt to overcome the resistance force.
The present invention intends to provide a brake cable adjusting device for a bicycle and the device has an adjusting bolt located at the inside of the brake lever. A sleeve is connected to the brake cable and the adjusting bolt threadedly extends the sleeve which is movable in parallel with the direction of the tension force of the brake cable. By this way, the adjusting bolt is easily rotated.